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MONDAY, Aug. 5 (HealthScoutNews) -- In a study that
may shed some light on the environmental triggers of auto-immune
disorders, researchers have found that genetically modified mice
with lupus get sharply worse when exposed to a constituent of mineral
oil.
The chemical, called pristane, had previously been
shown to cause the debilitating disease in healthy rodents. Yet
in people, substances occasionally known to bring on lupus -- from
antibiotics to drugs that treat high blood pressure -- don't generally
make it worse in those already diagnosed with the condition.
So the new findings, reported this month in the journal
Arthritis and Rheumatism, were somewhat surprising, said Dr. Westley
Reeves, an immune system expert at the University of Florida College
of Medicine in Gainesville and the leader of the multi-center research
effort.
Reeves said the key to the discovery appears to be
a group of inflammatory proteins called cytokines. These proteins,
and especially interleukin-12, were elevated in mutant mice with
the lupus-like ailment when the animals were injected with pristane.
Normally, animals injected with the oil derivative
can be followed for six months or so. But those with the immune
disorder suffered massive kidney damage before half that long. They
also developed a slew of proteins, called antibodies, to their own
genetic material, though the significance of that surge isn't clear,
Reeves said.
Roughly half a million Americans suffer from lupus,
but women with the disease outnumber men by about 9 to 1. The condition,
which is most common in black women, is marked by many symptoms,
ranging from skin rashes and arthritis to sun sensitivity and kidney
disease. Lupus typically occurs between the ages of 15 and 45, prompting
some experts to believe that female reproductive hormones might
be involved in its onset.
Genes, stress and environmental factors all have been
tied to lupus flare-ups, though researchers aren't sure in what
proportions. Symptoms can be controlled by a variety of therapies,
including steroids and even drugs that treat malaria.
Reeves and his colleagues are intrigued by the anti-malarial
therapies, he says, because they reduce the activity of cytokines.
His group is now exploring whether this effect jibes with their
latest findings.
They are also looking at whether viruses and substances
that trigger cytokine production in humans may play a role in either
the appearance or aggravation of lupus.
Dr. Judith James, a lupus expert at the Oklahoma Medical
Research Foundation in Oklahoma City, said the latest work might
prove valuable to the study of the condition in people.
But she cautioned that to date, the gap between animal
models and the human form of the disease has been wide.
"We have no idea how this will be applicable" to patients,
James said.
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